In the past, haloalkylation of aromatic compounds such as benzene and its derivatives was usually carried out by reaction with a haloalkyl ether or by reaction with aldehydes and hydrochloric acid such as is described in "Friedel-Crafts and Related Reactions", volume II, part 2, page 659, G. Oloh, Editor. The drawback to such procedures has been the lack of specificity of isomers obtained and frequently poor yields. For example, the previous preparation in the literature, (Journal of Organic Chemistry, 17, 350, 1952), for p-methylthiobenzyl chloride from thioanisole reports poor yields of product. That product, in fact, contains a high proportion of ortho isomer. We have found a novel process wherein an aromatic compound having an alkylthio group therein is haloalkylated with a di-(alkoxy or aralkoxy) alkane in the presence of a Lewis acid containing at least one halogen atom. We have further found that by this process the preparation of p-methythiobenzyl chloride from thioanisole, for example, is accomplished in a much higher yield and with substantially higher isomeric purity than in its previous preparation.